In commonly owned U.S. Pat. No. 5,630,796, a noninvasive delivery system is described that entails the use of a needleless syringe. The syringe is used for transdermal delivery of powdered therapeutic compounds and compositions to skin, muscle, blood or lymph. The syringe can also be used in conjunction with surgery to deliver therapeutics to organ surfaces, solid tumors and/or to surgical cavities (e.g., tumor beds or cavities after tumor resection).
The needleless syringe is constructed as an elongate tubular nozzle, having a rupturable membrane initially closing the passage through the nozzle adjacent to the upstream end of the nozzle. Particles comprising a powdered therapeutic agent are located adjacent to the membrane. The therapeutic agent is delivered using an energizing means which applies a gaseous pressure to the upstream side of the membrane that is sufficient to burst the membrane, thereby producing a supersonic gas flow through the nozzle in which the particles are entrained.
As explained in U.S. Pat. No. 5,630,796, the particles comprising the therapeutic agent may be carrier particles that have been coated, for example, with genetic material, or may be particles of powdered therapeutic agents for all kinds of therapeutic use. With respect to delivery of powdered therapeutic agents per se, e.g., agents delivered without the aid of a carrier particle, general delivery parameters include a particle size preferably in the range of about 10-40 .mu.m, a particle density preferably in the range of about 0.5-2.0 g/cm.sup.3, and an initial velocity preferably in the range of about 200-2500 m/sec with a momentum density preferably in the range of 4-7 kg/sec/m.